Hydrocarbon conversion



Sept. 13, 1955 J. w. JEwELL ETAL HYDRocARBoN CONVERSION 2 Sheets-Sheet lFiled Nov. 26, 1949 v di ATTORNEYS Sept. 13. 1955 J. w. JEWELL. ET A1.2,717,867

- HYDRocARBoN CONVERSION Filed Nov. 26, 1949 2 Sheets-Sheet 2 .7INVENTOR. JOSEPH W. JEWELL BY WILLIAM B. JoHNsoN 54 www/ ATTORNEYSUnited States Patent Oee 2,7 l 7,86 7 Patented Sept. 13, 1955 2,717,867HYDROCARBON CONVERSION Joseph W. Jewell, Summit, and William B. Johnson,Far Hills, N. J., assignors to The M. W. Kellogg Company, Jersey City,N. J., a corporation of Delaware Application November 26, 1949, SerialNo. 129,676 13 Claims. (Cl. 2112-14) This invention relates to animproved process for continuously coking and distilling residualhydrocarbon oils, that is, oils which cannot be vaporized completelybecause of the presence of unvaporizable constituents and/orconstituents which decompose with formation of carbonaceous deposits ondistillation. Such oils are best exemplified by reduced crudes, whichare produced by subjecting crude oil to distillation to vaporize andremove lower boiling constituents. It will be understood, however, thatthe invention is applicable to the treatment of any such oil which it isadvantageous to distill under coking conditions, such as crude oil,light reduced crude, heavy reduced crude, heavy gas oils andhigh-boiling synthetic hydrocarbon oils which may be produced byreacting carbon monoxide and hydrogen or by hydrogenating solidcarbonaceous materials.

Continuous coking of hydrocarbon oils has certain advantages overpresent methods in which the coke is produced in large drums which mustbe emptied periodically. These advantages consist principally of thelower investment and operating cost of continuous coking. However, it isdifficult in continuous coking processes to provide for positive controlof the soaking time of the coke particles, the coking reactiontemperature, residence time of the vaporized oil in the coking zone, andseparation of vaporized oil from the coke.

An object of the invention is to provide for coking hydrocarbon oils, animproved process in which the soaking time of the coke is controlledunder conditions in which all the coke particles are subjected tosoaking treatment for approximately the same length of time.

Another object of the invention is to provide an improved coking processin which the coking reaction temperature may be readily controlled, orchanged in response to changing requirements of the process.

Another object of the invention is to provide an improved coking processin which the residence time of the vaporized oil in the coking zone isheld to a minimum.

Another object of the invention is to provide a process which isadaptable to the treatment of feed stocks of widely varyingcharacteristics.

Another object of the invention is to provide a process for producing acoke of high porosity.

Further objects of the invention will be made apparent by the followingdescription of the improved process.

The improved process will be described by reference to the accompanyingdrawings which are diagrammaticV representations of apparatus suitablefor carrying out the process. It will be understood that the apparatusshown merely illustrates arrangements suitable for carrying out theprocess and that the process is capable of other embodiments beyond thephysical limitations of the apparatus shown in the drawings.

In the drawings:

Figure 1 is a diagrammatic View in elevation of an assemblage ofapparatus for carrying out the coking process,

Figure 2 s an enlargement of a portion of Fig. 1,

Figure 3 is a sectional view, at line 3-3 of Fig. 2,

Figure 4 illustrates a modification of the coking drum in which meansare provided for pulverizing the product coke,

Figure 5 is an enlarged View of a portion of Fig. 4, and

Figure 6 is an enlarged view of a portion of Fig. 5.

Referring to Fig. 1, a reduced crude oil is supplied to the processthrough line 10, which connects with a heat exchanger 11. The reducedcrude is preheated at 11 and the preheated oil is then transferredthrough line 12, to the entrance of a furnace 13 wherein the reducedcrude is further heated. The preheated oil is discharged, from furnace13, into line 14 through which it ows into fractionating tower 15 at anintermediate point. The oil is preheated at 13 to a temperature highenough to vaporize a portion of the oil as it is discharged into tower15. Fractionating tower 15 is provided, with gas and liquid Contactmeans, such as bubble trays and bales, and is operated under temperatureand pressure conditions effective to strip from oil charged thereto alllight constituents undesired in the oil to be subjected to cokingtreatment and separate distillate fractions comprising an overhead,gasoline, fraction and an intermediate, gas oil, fraction. In tower 1Sthe reduced crude oil undergoes separation into vaporized andunvaporized portions, the unvaporized portion flows downwardly inconntercurrent contact with oil vapors from the coking zone, which areintroduced into tower 15 at a low point from line 16.

By this treatment further preheating of the unvaporized portion of thereduced crude oil is effected and finely divided coke particles carriedinto tower 15, in suspension in the oil vapors from line 16, areentrained in the unvaporized portion of the reduced crude. The liquidwhich collects in the bottom of tower 15 comprises unvaporized portionsof the reduced crude charge as well as oil condensed from the vaporsfrom line 16 and is withdrawn therefrom through line 17, by means ofVpump 18, and passed to the coking treatment. The various treatments ofthe reduced crude described above are controlled to supply the oil tothe coking treatment,

f through line 17, at a temperature of approximately 650 to 750 F.

In carrying out the coking treatment, the preheated oil is contactedwith hot finely divided coke in a coking zone in which there ismaintained a horizontally extended bed of finely divided colte, aeratedby means of inert gases flowing upwardly therethrough at a velocity atwhich the bed in maintained in a relatively dense fiuidized condition.The liuidized bed of coke may be maintained in any suitable vessel, suchas horizontally elongated drum 19 which may be cylindrical in shape. Indrum 19 the iluidized bed of coke whose upper surface is indicated bydotted line 21 Ais supported on a perforated distribution plate 20 whichextends across drum 19 from side to side and from one end to a cokewithdrawal passageway opening into the other end of drum 19 at a lowpoint. Distribution plate Ztl is adapted to support a relatively thinbed of coke which moves continuously from the coke charging point to thecoke withdrawal passageway, that is, from right to left in Fig. 1.

Distribution plate 20 is arranged to present a generally horizontalupper surface. The movement of the bed of coke laterally from right toleft may be produced by the displacing action of coke added to the bedat the right end of drum 19, if the upper surface of plate 20 issubstantially exactly horizontal. However, this produces a coke bedwhich varies in depth, from a maximum near the coke inlet to a minimumnear the coke outlet. Therefore, it may be advantageous to incline thedistribution plate 20 downwardly toward the coke outlet suciently tocause lateral iiow of the coke bed at a suitable velocity, without theneed for any substantial variation in the bed depth. An inclination of lto l() degrees from the horizontal is usually sufficient, depending onthe bed depth required. Inclination of distribution plate 29 does notnecessarily require that drum 19 be mounted in a correspondinglyinclined position. However, economy of construction may require thatdrum 19 be mounted with its longitudinal axis parallel to the plane ofplate 20, and this is the arrangement illustrated in Figs. l and 2.

Distribution plate 20 is spaced sufficiently above the bottom of drum 19to provide an upper surface of sufficient width in proportion to thediameter of the drum to provide adequate aeration of the coke bed and toprovide a space in drum 19 under plate 20 for effective distributiontherein of aerating and stripping gases. These gases are introduced intodrum 19 at one or more points under plate 20, from lines 22 whichconnect with a supply line 23. The space under plate 20 may besubdivided by suitable partitions to permit passing differing quantitiesof gas through different sections of the coke bed. The distributionplate 20 may consist of one metal plate, or a plurality of plates,containing perforations whose size and number permit passage of aeratingand stripping gas up through the coke bed in a quantity and distributionsuch that the bed is uniformly aerated to the desired density and thedisplacement of volatile hydrocarbons from the bed is rapid andcontinuous. To effect uniform aeration and stripping the perforationsshould be as small, numerous, and uniformly distributed, as o possible.For this reason it is preferred to form plate 20 by mounting porousmetal plates in a suitable supporting grid. The methods for producingsuch plates are well known.

The hot finely divided coke and the preheated residual oil aredischarged into the right hand end of drum 19, preferably at a pointsubstantially above the upper surface of the iiuid bed of coke, underconditions such that the relatively vaporizable portion of the oil israpidly vaporized and the unvaporizable portion is absorbed by the hotcoke particles being introduced into drum 19. The relative proportionsof oil and hot coke charged to drum 19 are controlled to providesufficient absorbent surface in relation to the unvaporized portion ofthe oil, whereby the latter may be absorbed by the coke while the cokeremains sufficiently dry that it can be fluidized by the aerating andstripping gas flowing upwardly through distribution plate 20. The ratioin which coke and oil may be charged to drum 19, under satisfactoryconditions of operation, is affected by the volatility of the oil, andthe ratio may be controlled within limits by varying the temperature ofthe colte. Necessarily also the amount of oil which can be absorbed bythe coke is affected by the absorptive capacity of the circulating coke,which absorptive capacity may be controlled, to some extent, by varyingthe conditions under which the coke is burned after the cokingtreatment.

Preferably, the temperatures of the hot coke and oil charged into drum19 and the relative proportions of each are controlled to effect rapidvaporization of the oil and absorption of unvaporized constituents,whereby little or no liquid oil falls on the upper surface of the fluidbed of coke. This may be effected by discharging hot finely divided cokein an aerated condition into the interior of drum 19 at a high pointtherein while simultaneously spraying the hot residual oil into theinterior of drum 19 at a point nearby the point at which the aeratedcoke is being introduced. The spray of oil is directed into the aeratedmass of coke being introduced, to effect intimate contact of the hotcoke and oil. This produces rapid vaporization of a portion of the oiland the unvaporized portion is absorbed by the coke which is settledonto the upper surface of the fluid bed of coke distribution plate 20.

Preferably, the hot coke and oil being charged to the coking treatmentare mixed in a separate confined zone, which may be considered thevaporizing section of the coking zone, whereby part of the oil isvaporized and the unvaporized remainder is substantially completelyabsorbed by the hot coke, prior to discharge of the resulting mixtureinto drum 19 at a point from which the coke particles may settle ontothe fluidized bed of coke. The separate confined mixing and absorbingzone may be provided outside drum 19, but, in order to simplifyconstruction, it is provided in the upper interior of drum 19 bysuitably partitioning off a space around the inlets for the oil andcoke. This arrangement is shown in detail in Figs. l and 2, in which apartition in the form of a truncated cone 24, open at the lower smallend, is attached to the upper interior wall of drum 19. Line 17 connectswith a spray head 25 mounted at the top of drum 19 and arranged to spraythe hot residual oil downwardly within the vaporizing section, of thecoking zone, defined by partition 24. The finely divided hot coke forthe coking treatment is supplied from standpipe 26 as an aerated mass.The rate of supply of the hot coke is regulated by means of slide valve27 in the lower end of standpipe 26. The hot finely divided coke fromstandpipe 26 is discharged into the mixing section of the coking zoneprovided by partition 24 and into intimate contact with the oil beingsprayed therein. In order to promote intimate mixing, the hot coke istransferred from standpipe 26 into the vaporizing section through aplurality of branch lines 28. Two of these are provided in thearrangement illustrated in the drawing but it is evident that the hotcoke may be distributed through at many as such supply lines as ispractical, to promote uni form distribution of the coke into the oilspray.

To assist in the mixing of the hot coke and oil within the vaporizingsection of the coking zone, it may be desirable to introduce extraneousgas directly into the mixing section. For this purpose, line 29 isprovided to connect line 23 with a plurality of tangential inlets,through partition 24, into the mixing section of the coking zone. Thetangential introduction of the extraneous gas from line 24 throughinlets 30 produces a swirling movement of the coke particles and oildroplets whereby there is intimate contact of the oil and hot cokewithin the vaporizing section and prior to discharge of the resultingmixture of oil vapors and hot coke, through the exit 31 of partition 24,into the soaking section of thc col/.ing zone.

The hot coke and oil are mixed in proportions such that oil notimmediately vaporized may be absorbed completely by the coke particlesWhile remaining in a relatively dry non-adhering condition in which theymay be maintained as a dense free-flowing, fiuidized mass ondistribution plate 20 by the aerating and stripping gas fiowing upwardlytherethrough. It is preferred that vaporization of oil and absorption ofthe residue shall be accomplished solely by the coke with which the oilis first contacted in the mixing zone and that substantially nounabsorbed liquid oil be precipitated onto the surface 2l of the cokebed. vaporization of the oil may be further promoted by preheating tovaporizing temperatures the gas injected into the vaporizing zonethrough inlets 30.

The ratio in which the coke and oil are mixed to effect the desiredvaporization and absorption of the oil depends upon the temperatures ofthe coke and oil, the distillation characteristics of the oil, theproportion of the oil which is unvaporizable, and the composition of theunvaporizable portion of the oil. For colzing oil, which has beenpreheated to a temperature just short of vaporization, the coke and oilmay be mixed in a weight ratio of 1:1 to l0:l, preferably 6:1 to 2:1depending on the temperature of the coke, which may be preheated to 1900to l500 F., and the ratio of vapor to liquid after mixing.

The time of residence of the oil and hot coke in the mixing andvaporizing zone is such that vaporization of the readily vaporizablecomponents of the oil is the principal effect of the mixing of thepreheated oil and hot coke, although some decomposition incidental tocoking may be initiated in that zone. In the preferred modification ofthe invention, as illustrated in Fig. l, it was desired to separate theeluent vapors from the hot coke rapidly whereby cracking of vaporizedhydrocarbons is kept to a minimum. It is preferred therefore to limitthe residence time of the oil and coke in the confined mixing zone tothe time required to effect substantially complete vaporization.However, it is within Vthe scope of the invention to contact the oil andhot coke in a mixing Zone in which substantial coking of the residualcomponents of the oil on the coke particles is obtained.

In the preferred modification, illustrated in Fig. l, the mixture of oilvapors and hot coke containing deposited residual hydrocarbons isdischarged through opening 31 into the interior of drum 19, andpreferably above the level of the iiuidized bed of coke, whereby thevapors are quickly separated from the hot coke particles and arewithdrawn overhead to suitable recovery equipment.

The coke particles, on which residual components of the oil areundergoing further distillation and decomposition, are precipitated ontothe iluidized bed of coke whose upper level is indicated at 21. Due tothe displacing effect of the added coke particles and any inclination ofthe plate 20, the coke bed ows continuously from the right hand end ofdrum 19, at which the coke is added, to the left hand end. As pointedout above, the coke bed is maintained in a uidized condition by thepassage of aerating and stripping gas upwardly therethrough. Such gasmaintains the coke bed in a flowable condition and displaces, from thevoids between the coke particles, hydrocarbon vapors released from thecoke particles as the result of distillation and cracking ofhydrocarbons deposited thereon.

The time of residence of the coke particles in the fluid bed in drum 19is sufficient to provide the soaking time required to complete thecoking of the residual hydrocarbons deposited on the coke particles andthe evolution of hydrocarbons released by the coking reaction. Thisrequires, ordinarily, a residence time of 60 to 300 seconds, dependingupon the temperature of the coke bed. The rate of lateral flow of thecoke bed is governed by the rate at which coke is introduced into drum19 in relation to the bed of coke at right angles to the direction ofits lateral now. The inclination of the plate 20 assists lateral ilowand permits flowing the bed laterally at a satisfactory rate with nosubstantial difference in the bed depth at the ends thereof. However,inclination of plate 20 is not necessary to satisfactory lateralmovement of the bed. Ordinarily the coke bed may be fluidized underconditions providing for uniform residence time of the particles atlateral velocities of 0.1 to 0.5 feet per second.

rihe lateral flow of the coke bed in accordance with the improvedprocess provides for uniform residence time of the coke particles andalso permits control of the residence time of all the coke particles inthe soaking zone, that is, the zone traversed by the coke particles inpassing from the vaporizing zone to the exit of drum 19. The residencetime of the coke particles may be varied by varying the rate at whichcoke is discharged into drum 19 and by varying the quantity of coke indrum 19. ln this manner the improved process provides means forsubjecting each coke particle to the residence time required foreifecting the desired decomposition and distillation of the particularoil undergoing coking treatment.

The depth of the coke bed in drum 19 is maintained relatively low,preferably 0.5 to 5.0 feet whereby effluent vapors are quickly strippedfrom the bed by means of aerating and stripping gas flowing upwardlytherethrough at velocities suiciently low to avoid agitation of the bedwhich would interfere with uniformity of residence time of the cokeparticles.

The quantity of stripping and aerating gas introduced into drum 19through inlets 22 for passage up through the coke bed depends on thethickness of the bed and the quantity of stripping gas needed. It ispreferred to utilize quantities of stripping and aerating gas such thatthe gas passes through the bed at relatively low velocity, whereby undueturbulence of the bed is avoided. Ordinarily it is desired to introducethe gas from inlets 22 at a rate such as to produce superficial upwardvelocity of 0.1 to 2.0 -feet per second, preferably 0.2 to 0.8 feet persecond. The superficial velocity is the velocity which would be assumedby the gas upon emerging from the orifices of distrlbution plate 20 inthe absence of a bed of coke but at the coke bed temperature andpressure. It is preferred that the quantity of stripping gas and the beddepth be correlated to maintain a residence time of the stripping gas 1nthe coke bed within the range of l to 6 seconds. Thus when the strippinggas is introduced at a rate corresponding to a superficial velocity of 2feet per second into a bed of coke maintained in aerated condition bysuch gas at a depth of approximately 5 feet, the aerating gas will passthrough the coke bed in approximately 2 seconds. Likewise when aeratinggas is introduced at a superficial velocity of 0.1 foot per second itwill pass through a 0.5 foot bed in approximately 3 seconds.

At the left hand, or discharge, end of drum 19 the fluid bed of cokeoverows into a suitable withdrawal passageway 32 opening into the bottomof drum 19. If necessary aerating gas may be introduced into passageway32, from line 33 which connects with line 23, to maintain the withdrawncoke in aerated condition. The coke is discharged from passageway 32into a screw conveyor 34 through which the coke is passed to the burningzone. It may be desirable to subject the coke withdrawn from drum 1.9 toa grinding treatment prior to burning, to reduce any large particles ofcoke which are formed by agglomeration or by accretion of coke fromdecomposed oil. Any suitable grinding means may be used for thispurpose. Conveniently, screw conveyor 34 may be made to serve thispurpose Vand the grinding eect may be promoted by mounting suitablegrinding elements on the shaft of the screw of conveyor 34. In thisarrangement the screw conveyor 34 provides: means for controlling therate of withdrawal of coke from drum 19, means for grinding thewithdrawn coke, and means for transferring the withdrawn coke to theburning zone.

The outlet vof conveyor 34 connects with an elongated conduit 35 inwhich is located the burning zone for the coke. In conduit 35 the cokefrom drum 19 is carried at relatively high velocity in a gas streamcontaining oxygen to support the partial Vcombustion of the coke whichis desired to raise the coke to the temperature needed to carry out thecoking of additional quantities of residual oil. Ordinarily the coke isdischarged to drum 19 at a temperature of approximately 950 to 1l50 F.The heat required to complete coking ordinarily results in the cokebeing cooled by 125 to 250 F. in passing through drum 19. Consequentlythe coke introduced into conduit 35 is sufficiently hot to initiatecombustion upon contact with air introduced at the lower end of conduit35. The air is supplied by a blower 36 through line 37. If it is desiredto preheat the air, when starting up or for control purposes, an airheater 33 may be provided at the lower end of conduit 35. A portion ofthe air from line 37 from blower 36 is mixed with fuel gas from line 39at the bottom of heater 38 while the remainder of the air is introduceddirectly into air heater 38 b y means of line 40.

The regeneration gas and suspended coke is iiowed upwardly throughconduit 35 at a relatively high velocity of 10-50 feet per second,preferably 15-25 feet per second, as a relatively' dilute suspension.The quantity of regeneration gas employed is the amount necessary toburn coke in the burning zone to the extent necessary to impart, to thatportion of the hot coke recirculated in the system, the heat requiredfor vaporizing and coking the oil. Air is normally employed as theregeneration gas and it is introduced at a rate of 0.5 to 2.0 cu. ft.(measured at standard condition) per pound of coke leaving the cokingchamber.

In the burning zone the coke is carried in suspension in the stream ofregeneration gas. At least a part of the path of iiow of theregeneration gas in the burning zone is in a vertical direction, asshown in Fig. l. This serves to lift the hot coke to a point ofdischarge, from the burning zone, which is substantially elevated abovethe coking zone, and also serves to lengthen the residence time of thecoke particles in the burning zone. In the vertical section of theburning zone substantial slippage of the coke particles in the owing gasstream occurs, the degree of slippage varying with the gas velocity. Ata gas velocity in the preferred range of 15-25 feet per second theconcentration of coke in the gas stream may be, in the vertical sectionof the burning zone, two or three times the inlet concentration. Thelength of the burning zone is designed to retain the coke particlestherein for a time sufficient to raise their temperature at least to thetemperature at which they are desired for use in the coking step.

The supply of oxygen to the burning zone ordinarily is limited to theamount necessary to cause combustion which will raise the temperature ofthe coke particles to the desired elevated temperature. However, undersome conditions it may be desirable to apply cooling treatment at somepoint in the burning Zone. This may be necessary, for example, underconditions wherein it is necessary, in order to decrease the volatilecontent of the circulating coke, to burn the coke at a highertemperature than the temperature at which it is desired to employ thecoke for vaporization and coking of the oil feed.

The exit of conduit 35 opens into the interior of an enlarged settlinghopper 41 in which the flue gas and hot coke particles are separated. Toassist in settling the coke particles conduit 35 in connected to hopper41 in a manner to discharge the suspension in a downward direction. Tofurther assist in settling the coke particles conduit 35 is extendeddownwardly in hopper 41 to a relatively low point, as indicated inFig. 1. The settled coke particles are accumulated in the lower part ofhopper 41 and the resulting mass is maintained in a iiuidized condition,which may be promoted if necessary by the injection of aerating gas intohopper 41 at a low point.

Additional means may be provided to separate the ner particles of cokefrom the llue gas. Such means conveniently may comprise one or morecyclone separators which, as shown in Fig. l, conveniently may belocated in the upper interior of hopper 41. The tine coke separated incyclone 42 is returned to a low point in hopper 41 by a suitable dip-leg43. The ilue gas emerges from the cyclone separater 42 and from hopper41 through line 44 which may be provided with a pressure control valve45. The ilue gas thus discharged from the system may be passed tosuitable heat exchange steps for recovery of the heat contained thereineither before or after pressure release or may be discharged to theatmosphere.

Instead of, or in addition to, the use of separating devices of thecyclone type, it may be desirable to pass the iiue gas through filteringmeans to effect a suicient recovery of the coke particles from the uegas. Conveniently such filters may be located in the upper interior ofhopper 41.

Regardless of the extent of stripping to which the coke is subjected asit ows in the fluid bed in drum 19 toward outlet 32, the coke introducedinto burning Zone 35 contains a substantial proportion of volatilecombustible material. A substantial part of the combustion which occursin zone 35 results from the burning of such volatile matter. This tendsto increase the porosity of the circulating coke. It may cause somespalling of the coke with consequent decrease in particle size. This maybe desirable since there is an increase in particle size in the coldngzone. Under controlled combustion the volatile materials ispreferentially burned in the burning zone. Normally the heat generatedby burning a part of the volatile material is suficient to support theheat of coking in the coking zone.

The excess coke produced in the process, that is the coke laid down bythe oil and not consumed in the process, is withdrawn from the processpreferably from hopper 41, as at that point in the circulation of thecoke it is found to be in the best condition for withdrawal as a productof the process.

In order to maintain the circulating mass of coke in the finely dividedcondition which is desirable for maintenance of the aerated coke bed indrum 19, it may be advantageous to effect a degree of classification ofthe coke particles in hopper 41 whereby the relatively more coarseparticles are withdrawn as the product coke, while the finer cokeparticles are recirculated. In the arrangement shown in Fig. l theproduct coke is withdrawn from the bottom of hopper 41 through asuitable standpipe 46 provided with a control slide valve 47. Standpipe26 is connected at its upper end with hopper 41 at a point somewhatabove the lower end of standpipe 46. The aeration of the settled mass ofparticles which covers the inlets of both standpipe 26 and 46 mayproducesutiicient classitication of the coke particles whereby the smallproportion of the coke withdrawn through standpipe 46 consistspredominantly of larger particles. The rate at which coke is withdrawnthrough standpipe 46 is only a small fraction of the rate withdrawnthrough standpipe 26, as ordinarily the coke recirculated throughstandpipe 26 is 20 to 40 times the quantity of coke withdrawn as productthrough standpipe 46.

To assist in the classification of the coke particles in hopper 41 avertical partition 48 is provided to divide the bottom part of hopper 41into two sections. The lower end of conduit 35 is arranged to dischargethe coke and gas over the inlet to standpipe 46, whereby materialentering standpipe 26 must ow over the partition 48. The degree ofclassification required in the material withdrawn through standpipe 46may be controlled by varying the amount of aerating gas admitted abovethe entrance to standpipe 46, from line 78. The minimum aerationvelocity necessary to maintain fluidization above standpipe 46 willresult in little classification, whereby the particles withdrawn throughstandpipe 46 will have substantially the same particle size range as thecoke discharged frorn conduit 35. increasing the aeration velocity, byincreasing the volume of aerating gas from line 78, will causeelutriation, the degree of which can be varied as desired. If accretionin the coking zone rcsults in an increase in the average particle sizeof the coke which is not compensated for in the burning zone, thequantity of coke withdrawn through line 46 may be increased over theamount equivalent to the excess coke,

so that a portion of the coke thus withdrawn may be ground up andreturned to the system as fines.

The recirculated particles are withdrawn through standpipe 26 fortransfer to the vaporizng zone in the manner described above. Instandpipe 26 the coke is maintained in a suitable fluidized condition atrelatively high densities. Ordinarily the downward velocity of the cokein standpipe 26 is sufficient to retain the aerated condition of thecoke or it may be desirable to inject r aerating gas at intervals alongthe length of standpipe The length of standpipe 26 and, consequently,the elevation at which hopper 41 is mounted above coke drum 19 depend onthe pressure drop experienced in the circu lation of the coke from drum19 through the burning zone and the settling hopper 41 and the densityof the coke in standpipe 26. Ordinarily the pressure drop isapproximately 5 pounds per square inch in owing the coke from drum 19 tothe lower part of hopper 41. The pressure drop on the coke in flowingthrough slide valve 27 is maintained at approximately 5 pounds persquare inch. Consequently it is desired ordinarily to provide by meansof standpipe 26 an increase in pressure from the top to the bottomthereof of approximately pounds per square inch. If the density of thecoke in standpipe 26 is approximately 3i) pounds per cu. ft. it issatisfactory to provide standpipe 26 with a length such that it rises avertical distance of approximately 48 ft.

The stripping and aerating gas introduced into drum 19 through lines 22,29 and 33 and into standpipe 26 conveniently may be steam although otherinert gas such as hydrocarbon gas produced in the process may beernployed. Steam is preferred, however, as it introduces fewerdiiiiculties in the recovery of the volatile products of the process.Any suitable aerating gas may be introduced into the lower part ofhopper 41, such as steam, or ilue gas.

The volatile products of the process are withdrawn from high points indrum 19 preferably through a plurality of outlet lines 49 which connectwith line 16 for passage of the vapors to fractionating tower in themanner described. A plurality of outlet lines 49 distributed along thelength of drum 19 is preferred in order to minimize the time ofresidence of the product vapors in drum 19, whereby cracking of thevaporized hydrocarbons is kept to a minimum. Cooling means may beassociated with the vapor outlet lines or line 16 to elect promptcooling of the vapors to non-cracking temperatures. Heat exchange may beprovided for this purpose, or means to inject cooling liquid or vaporsdirectly into the vapor lines.

ln fractionating tower 15 the vapor product is subjected to scrubbingwith the charge oil, as described above, to vaporize portions of thecharge oil, scrub from the product vapors fine coke particles carriedtherein in suspension from drum 19, and condense the highest boilingportion of the vapors for recycling to the coking zone. In the upperportion of tower 15, above the section in which the scrubbing treatmentis carried out, the product vapors and the vaporized portion of thecharge oil are subjected to fractionation in any suitable manner torecover the products of the process which include a gas oil fraction, agasoline fraction and a gas fraction. The heat for the fractionatingtreatment is supplied to tower 15 in the product vapors from line 16 andin preheated feed from 1tine 1d. Cooling at the upper end of the toweris provided by refluxing. The overhead fraction is withdrawn throughline Si? which passes through cooler 51 in which condensation or' thenormally liquid components is etfected. Separation of the condensatefrom the uncondensed gas is carried out in drum 52, from which the gasis withdrawn through line 53. Any water contained in the product vapors,as the result of the use of steam in the system, is condensed at thispoint and withdrawn from drum 52 through line 54, provided with pump 55.The liquid hydrocarbon fraction separated in drum 52 is withdrawnthrough line 56, provided with pump 57. A portion of this condensate isreturned by pump 57 through line 53 to the top of tower 15 to providethe retluxing of the tower necessary for the fractionation operation. Aportion of the condensate delivered by pump 57 is withdrawn by line 59as a gasoline or naphtha product oi the process.

A gas oil fraction is recovered by withdrawing a liquid stream fromtower 15 at an intermediate point through line oil. This side stream isdelivered by line 60 into a stripping tower 61 in which the side streamis heated to strip light components therefrom, these being withdrawnoverhead through line 62 and introduced into tower 15 at a higher point.The stripped gas oil is withdrawn as a product of the process throughline 63 by means of pump 6a, a cooler 65 being provided in line 63 forcooling the gas oil product to a suitable low temperature. A portion ofthe side stream withdrawn from tower 15 through line 6i) may be divertedtherefrom through line 66 by means of pump 67 and passed through heatexchanger 11 and cooler 68 prior to being returned to a suitable pointin K opening 76 in the bottom thereof. Ball tower 15 through lines 69and 70, as an intermediate reilux. A

lt will be understood that the introduction of the charge oil into tower15 depends on the presence of readily vaporizable components therein.Ordinarily a crude oil or a reduced crude oil or a heavy gas oil ischarged to the process by introducing it into tower 15 in the mannerdescribed. Oils which have been substantially denuded of componentswhich can be vaporized at non-coking temperatures may be introduced intothe process directly through line 17, after being preheated to asuitable temperature. However it may be desirable to introduce reducedcrudes containing volatile constituents directly into line 17, in whichcase they are preheated to a higher temperature.

The operation of the process described above may be illustrated by thefollowing specific example of the treatment of a Kansas reduced crudehaving a gravity of 25 A. P. I. The reduced crude is charged to theprocess through line 10 and distilled in fractionating tower 15 underconditions effective to produce a straight run gas oil representing 48wt. per cent of the oil charge and a residual oil having a gravity of18.5 A. P. I. This residual oil plus recycle oil is treated inaccordance with the improved process to produce distillate oil in thecoking zone equivalent to at least 36 wt. per cent of the charge oilfrom line 1d while producing a dry gas to the extent of 4.1 wt. per centof the charge oil and recovering a coke product through standpipe 46equivalent to 11.9 wt. per cent of the charge oil from line 10.

Example Outlet temperature of furnace 13 Feed oil temperature in line 17Y 1.5 ft. 25 1b./cu. ft.

Lateral velocity of coke bed 0.4 ft./sec. Length of coke bed 54 ft Steamthrough line-s 10 wt. per cent on feed.

Steam throughline 29 5 wt. per cent on feed.

Air in line 35 3.8 St. cu. ft,/1b

' feed oil.

Gas velocity in line 35 20 ft./sec.

Circulating coke to make coke 16 t 1.

Coking time secs.

A modiiication of coking drum 19 is illustrated in Figs. 4, 5 and 6. Inthis modification means are provided, within the drum, for continuouslyreducing large coke particles formed in the coking operation. In thisarrangement a hopper 71 is interposed between the lower end ofdistribution plate 20 and a hopper 72 which is provided to direct thecoke to draw-off line 73. In this modification a slide valve 74%V isprovided in line 73 to control the rate of withdrawal of coke.

The coke iiows from the lower end of distribution plate 20 to and acrosshopper 71. Aera'ting gas is passed upwardly through the coke mass duringthis passage whereby classification occurs, with the more coarseparticles being concentrated in the bottom of hopper 71. By this meansthe coarser coke particles are directed by hopper 71 into a ball mill7El which connects with hopper 71 through an mill 75 is provided with aplurality of steel or ceramic balls which are agitated in the lowerconical portion thereof by means of steam jets introduced tangentiallythrough line 77. The movement of the balls reduces the larger cokeparticles to smaller particles capable of being lifted upwardly out ofthe ball mill and back to hopper 71 by the steam from line 77 whichrises upwardly in the ball mill and acts as the aerating gas in hopper71. By this means the reduction of the coarser coke particles is carriedout continuously inside the coking zone.

The cpcraion of the colring process may be started by 11 supplying neparticles from any source. Petroleum coke is preferred but other cokemay be used, as well as finely divided siliceous materials, such asbentonite clay. Carbonaceous starting materials may be heated initiallyto the desired high temperature by combustion with preheated air in zone35. Non-carbonaceous materials may be heated to the desired temperatureby heated air from heater 38. The starting materials are graduallyreplaced in the process by coke particles formed from the oil beingprocessed, so that normal operation involves a circulating mass ofparticles of coke formed from the oil.

We claim:

l. A process for coking and distilling residual hydrocarbon oil whichcomprises forming and maintaining in the lower part of a coking zone ahorizontally extended bed of nely divided hot coke, owing aerating gasupwardly through said coke bed to maintain all parts thereof in arelatively dense iiuidized condition whereby the bed is capable oflateral flow, discharging a mixture of hot finely divided coke andresidual oil into the coking zone at one end of the coke bed whereby theadded coke merges with the coke bed and the residual oil is partlyvaporized by the heat of the added hot coke and the unvaporized portionis deposited on the surfaces of hot coke particles for distillation anddecomposition by the heat of the coke continuously stripping said oilvapors from said horizontally flowing bed by means of said aerating gasto diminish the amount of oil vapor in said bed as it flows downstream,maintaining a disengaging space above said horizontally flowing bed forcollecting said vaporized components of said residual oil above saidbed, withdrawing said oil vapor from said disengaging space withoutfurther contact with said bed, withdrawing coke from the uidized bed atan edge thereof horizontally distant from the point of introduction ofhot coke into the coking zone whereby the coke bed flows laterally fromthe point of introduction of hot coke into the coking zone to the pointof withdrawal thereof from the uidized bed, subjecting the cokewithdrawn from the coking zone to partial combustion to heat the cokesubstantially above the temperature of withdrawal, and discharging saidheated coke into said coking zone in the manner described.

2. The process of claim l wherein coke withdrawn from the fluid-like bedin the coking zone is subjected to grinding treatment to reduce theaverage particle size thereof prior to introduction into the burningzone.

3. A process for coking and distilling a residual hydrocarbon oil whichcomprises, continuously supplying hot petroleum coke in finely dividedform to an oil vaporizing section of a coking zone, intimately mixingthe hot coke with residual oil in the oil vaporizing section to effectvaporization of a portion of the oil and decomposition of unvaporizedconstituents of the oil with deposition of carbon on the surfaces of thecoke particles, discharging into one end of a horizontally elongatedsoaking section of the coking zone the mixture of oil vapors and cokeparticles bearing unvaporized constituents of the oil undergoingdecomposition, settling the coke particles out of the oil vapors in thesoaking section of the coking zone, maintaining the settled coke as arelatively dense uid-like mass by the passage of aerating and strippinggas upwardly therethrough, owing the fluid-like bed of coke horizontallyfrom the inlet of the soaking section of the coking zone to a cokedischarge point at the opposite end of said section, withdrawing cokefrom said coking zone at the coke discharge point, continuouslystripping hydrocarbon vapors from said horizontally flowing bed as saidvapors are formed therein and separately withdrawing said vapors andstripping gases from said coking zone above said fluid-like coke bed,suspending withdrawn coke in air under conditions effective to initiatecombustion, transporting the suspension through an elongated burningzone to effect partial combustion of the coke to heat it to atemperature substantially higher than the temperature at which the cokeis discharged from the coking zone, discharging the suspension of ue gasand heated coke into a settling zone, withdrawing a minor portion of thecoke from the settling zone as a product of the process, andtransporting the remainder of the coke separated in the settling zone tothe oil vaporizing step, as described.

4. The process of claim 3 wherein the mixture of oil vapors and cokeparticles bearing unvaporized constituents of the oil undergoingdecomposition is discharged into the coking zone above the level of therelatively dense fluid-like mass of coke particles therein.

5. The process of claim 4 wherein the mixture of oil vapors and cokeparticles is discharged downwardly into the space in the coking zoneabove the fluid-like bed of coke particles.

6. The process for coking and distilling a residual hydrocarbon oilwhich comprises, maintaining a column of hot petroleum coke in finelydivided form wherein the mass of coke is maintained in a relativelydense fluid-like condition by reason of the presence of aerating gastherein, continuously discharging hot coke from the lower end of saidcolumn into an oil vaporizing section of a coking zone, intimatelymixing the hot coke in lthe oil vaporizing seetion with residual oil toeffect vaporization of a portion of the oil and decomposition ofunvaporized constituents of the oil with deposition of carbon on thesurfaces of the coke particles, discharging into one end of ahorizontally elongated soaking section of the coking zone the mixture ofoil vapors and coke particles bearing unvaporized constituents of theoil undergoing decomposition, settling the coke particles out of the oilvapors, maintaining the settled coke as a relatively dense uid-like massby the passage of aerated and stripping gas upwardly therethrough, owingthe fluid-like bed of coke horizontally from the inlet of the soakingsection of the coking zone to a coke discharge point at the opposite endof said section, withdrawing coke from said coking zone at the cokedischarge point, continuously stripping hydrocarbon vapors from saidhorizontally flowing bed as said vapors are formed therein andseparately withdrawing said vapors from said coking zone above saidfluid-like coke bed, suspending withdrawn coke in air under conditionseffective to initiate combustion, transporting the suspension through anelongated burning zone to effect partial combustion of the coke to heatit to a temperature substantially higher than the temperature at whichthe coke is discharged from the coking zone, discharging the suspensionof flue gas and heated coke into a settling zone, and supplying cokeseparated in said settling zone to the upper end of said first mentionedcolumn of nely divided coke.

7. A process for coking and distilling hydrocarbon oil, which includesthe steps of z flowing through an elongated coking zone a substantiallyhorizontal stream of finely divided hot coke, the depth of said streambeing shallow relative to its length in the direction of flow; flowingaerating gas upwardly through said stream to maintain it in a densefluidized condition in the lower part of said coking zone, with a moreor less distinct upper surface separating said stream from an overheadsettling region containing a gas-coke mixture of relatively low density;downwardly introducing hot finely divided coke into said coking zoneabove said upper surface and at an upstream point of said uidized cokestream, said coke having a temperature substantially above thetemperature of said tluidized stream; spraying said hydrocarbon oil onsaid freshly introduced hot coke at a ratio of oil to coke adapted topartially vaporize said oil and produce a mixture dry enough to fluidizein said uidized coke stream; depositing said mixture of introduced cokeand oil on the surface of said uidized stream and maintaining the ow ofsaid uidized stream at a rate which permits the distillation anddecomposition by heat of a portion of the oil deposited on the surfaceof said coke particles, and the conversion of the remainder to coke,thereby causing an accretion of coke, during the time required for saidstream to carrv said particles through said coking zone; con- 13tinuously stripping product vapor from said stream by means of upwardlyiiowing aerating gasto minimize the residence time of vaporized oil` offluidized coke; withdrawing product vapor from said settling regionabove said stream at points distributed along the iiow of said stream;withdrawing coke from a downstream point of said iiuidized coke stream;mixing saidwithdrawn coke with an oxygen-containing gas to partiallyburn said coke suiciently to supp'ly heat for recontacting with oilfeed,

and simultaneously transferring vsaid coke particles in 2 suspension insaid gas to a point of substantially higher elevation than the point ofintroduction of said particles into said coking stream; settlingparticles ofv partially burned and heated coke from said suspension, andiiowing them downwardly into said contacting zone in the mannerdescribed.

8. The process for coking and distilling a residual hydrocarbon oilwhich comprises: continuously supplying hot petroleum coke in linelydivided form to an oil vaporizing section of a coking zone, intimatelymixing the hot coke with residual oil in the oil vaporizing section toeifect vaporization of a. portion of the oil and decomposition ofunvaporized constituents of the oil with deposition of carbon on thesurfaces of the coke particles, discharging into one end -of ahorizontally elongated soaking section of the coking zone the mixture ofoil vapors and coke particles bearing unvaporized constituents of theoil undergoing decomposition, settling the coke particles out of the oilvapors, maintaining the settled coke as a relatively dense iiuid-likemass by the passage of aerating and stripping gas upwardly therethrough,separately withdrawing from a point above the Huid-like bed of coke inthe coking zone the hydrocarbon vapors separated therein, scrubbing saidwithdrawn vapors with said residual oil to entrain in said residual oilcoke particles carried out of the coking zone in suspension in saidvapors, thereafter passing the residual oil with entrained cokeparticles to the oil vaporizing step, iiowing the fluid-like bed of cokehorizontally from the inlet of the soaking section of the coking zone toa coke discharge point at the opposite end of said section, withdrawingcoke from said coking zone at the coke discharge point, suspendingwithdrawn coke in air under conditions effective to initiate combustion,maintaining the coke as a relatively dilute suspension thereof in saidair throughout a partial combustion of the coke to heat it to atemperature substantially higher than the temperature at which the cokeis discharged from the coking zone, separating the hot partially burnedcoke from the flue gases, and supplying the hot coke to the oil vaporingzone, as described.

9. The process for coking and distilling a residual hydrocarbon oilwhich comprises: continuously supplying hot petroleum coke in finelydivided form to an oil vaporizing section of a coking zone,intimately'mixing the hot coke with residual oil in the oil vaporizingsection to effect vaporization of a portion of the oil and decompositionof unvaporized constituents of the oil with deposition of carbon on thesurfaces of the coke particles, discharging into one end of ahorizontally elongated soaking section of the coking zone the mixture ofoil vapors and coke particles bearing unvaporized constituents of theoil undergoing decomposition, settling the coke particles out of the oilvapors, maintaining the settled coke as a relatively dense Huid-likemass by the passage of aerating and stripping gas upwardly therethrough,separately withdrawing from a point above the fluid-like bed of coke inthe coking zone the hydrocarbon vapors separated therein, flowing theuid-like bed of coke horizontally from the inlet of the soaking sectionof the coking zone to a coke discharge point at the opposite end of saidsection, withdrawing coke from said coking zone at the coke dischargepoint, suspending withdrawn coke in a stream of air flowing upwardly ata velocity such that the coke particles are carried therein as arelatively dilute suspension, the temperature of the coke and the airbeing such as to r owing aerating gas initiate combustion, flowing therelatively dilute suspension upwardly for a distance effective to heatthe coke by partial combustion thereof to a temperature substantiallyhigher than the temperature at which the coke is 'discharged from thecoking zone, separating the hot coke from the ue gas at a levelsubstantially higher than the level of the oil vaporizing section, andtransferring the separated hot coke downwardly to the oil vaporizingsection as a vertically elongated dense iiuidized column effective toovercome the pressure drop experienced by the coke in flowing throughthe coking and burning zones.

10. A process for coking and distilling a hydrocarbon oil, whichincludes the steps of iiowing through an elongated coking zone ahorizontally extended stream of iinely divided hot coke, the depth ofsaid stream being shallow relative to its length in the direction offlow; owing aerating gas upwardly through said stream to maintain it ina dense liuidized condition in the lower part of-said coking zone, witha more or less distinct upper surface separating said stream from anoverhead settling region containing a gas-coke mixture of relatively lowdensity; continuously introducing a mixture of hot finely divided cokeand residual oil into said coking zone at an upstream point of saidfluidized coke stream, said coke having a temperature substantiallyabove the temperature of said iiuidized stream at a ratio of oil to cokeadapted to partially vaporize said oil and produce a mixture dry enoughto iiuidize in said fluidized coke stream; maintaining the flow of saiduidized stream at a rate which permits the distillation anddecomposition of a portion of the oil deposited on the surface of saidcoke particles, and the conversion of the remainder to coke, therebycausing an accretion of coke, during the time required for said streamto carry said particles through said coking zone; continuously strippingproduct vapor from said stream by means of upwardly iiowing aerating gasto minimize the residence time of vaporized oil in said iiuidized coke;withdrawing product vapor from said settling region above 'said stream;withdrawing coke from a downstream point of said liuidized coke stream;mixing said withdrawn coke with an oxygen-containing gas to partiallyburn said coke suiiiciently to supply heat for recontacting with oilfeed, and simultaneously transferring said coke particles in suspensionin said gas to a point of substantially higher elevation than the pointof introduction of said particles into said coking stream; settlingparticles of partially burned and heated coke from said suspension, andflowing them downwardly into said contacting zone in the mannerdescribed.

1l. A process for coking and distilling a hydrocarbon oil, whichincludes the steps of iiowing through an elongated coking zone asubstantially horizontal stream of iinely divided hot coke, the depth ofsaid stream being shallow relative to its length in the direction offlow; flowing aerating gas upwardly through said stream to maintain itin a dense uidized condition in the lower part of said coking zone, witha more or less distinct upper surface separating said stream from anoverhead settling region containing a gas-coke mixture of relatively lowdensity; introducing hot finely divided coke into said coking zone at anupstream point of said iiuidized coke stream, said coke having atemperature substantially above the temperature of said liuidizedstream; spraying said hydrocarbon oil on said freshly introduced hotcoke at a ratio of oil to coke adapted to partially vaporize said oiland produce a mixture dry enough to i'luidize in said fluidized cokestream; maintaining the flow of said fluidized stream at a rate whichpermits the distillation and decomposition by heat of a portion of theoil deposited on the surface of said coke particles, and the conversionof the remainder to coke, thereby causing an accretion of coke, duringthe time required for said stream to carry said particles through saidcoking zone; continuously stripping product vapor from said stream bymeans of upwardly to minimize the residence time of vaporized oil insaid fluidized coke; withdrawing product vapor from said settling regionabove said stream', withdrawing coke from a downstream point of saiduidized coke stream; mixing said withdrawn coke with a gas to transfersaid coke particles in suspension in said gas to a point ofsubstantially higher elevation than the point of introduction of saidparticles into said coking stream; settling particles of coke from saidsuspension, and flowing them downwardly into said contacting zone in themanner described; heating said coke during said transfer steps to atemperature between 950 F. and 1150" F.; and introducing said hot cokeinto said coking zone at a rate such that the coke is not cooled to atemperature lower than 750 F. during its passage to said coke-dischargepoint.

12. A process for coking and distilling a hydrocarbon oil, whichincludes the steps of: owing through an elongated coking zone asubstantially horizontal stream of nely divided hot coke, the depth ofsaid stream being shallow relative to its length in the direction of ow;owing aerating gas upwardly through said stream to maintain it in adense uidized condition in the lower part of ysaid coking zone, with amore or less distinct upper surface separating said stream from anoverhead settling region containing a gas-coke mixture of relatively lowdensity; introducing hot nely divided coke into said coking zone at arelatively hot upstream point of said fluidized coke stream, said cokehaving a temperature substantially above the average temperature alongsaid uidized stream; spraying said hydrocarbon oil on said freshlyintroduced hot coke at a ratio of oil to coke adapted to partiallyvaporize said oil and produce a mixture dry enough to uidize in saidiluidized coke stream; owing said fluidized stream at decreasingtemperature and diminishing oil vapor content to a downstream dischargepoint; maintaining said ow at a rate which permits the distillation anddecomposition by heat of a portion of the oil deposited on the surfaceof said coke particles, and the conversion of the remainder to coke,thereby causing an accretion of coke, during the time required for saidstream to carry said particles through said coking zone; continuouslystripping product vapor from said stream by means of upwardly owingaerating gas to minimize the residence time of vaporized oil in saiduidized coke; withdrawing product vapor from said settling region abovesaid stream; withdrawing coke from a downstream point of said'fluidizedcoke stream; mixing said Withdrawn coke with an oxygen-containing gas topartially burn said coke suiciently to supply heat for recontacting withoil feed, and simultaneously transferring said coke particles insuspension in said gas to a point of substantially higher elevation thanthe point of introduction of said particles into said coking stream;settling particles of partially burned and heated coke from saidsuspension, and owing them downwardly into said contacting zone in themanner described.

13. A process as described in claim 1() in which said coking isinitiated by introducing hot non-carbonaceous particles into said cokingzone at said upstream point to start the ow of uidized solids throughsaid horizontally extended coking zone.

References Cited in the tile of this patent UNITED STATES PATENTS2,328,325 Butikofer Aug. 31, 1943 2,339,932 Kuhl Ian. 25, 1944 2,362,270Hemminger Nov. 7, 1944 2,371,619 Hartley Mar. 20, 1945 2,385,446 Jewellet al Sept. 25, 1945 2,419,245 Arveson Apr. 22, 1947 2,443,714 ArvesonJune 22, 1948 2,445,328 Keith July 20, 1948 2,462,366 Davies et al. Feb.22, 1949 2,492,998 Lassiat Jan. 3, 1950 FOREIGN PATENTS 419,444 GreatBritain Nov. 8, 1934

1. A PROCESS FOR COKING AND DISTILLING RESIDUAL HYDROCARBON OIL WHICHCOMPRISES FORMING AND MAINTAINING IN THE LOWER PART OF A COKING ZONE AHORIZONTALLY EXTENDED BED OF FINELY DIVIDED HOT COKE, FLOWING AERATINGGAS UPWARDLY THROUGH SAID COKE BED TO MAINTAIN ALL PARTS THEREOF IN ARELATIVELY DENSE FLUIDIZED CONDITION WHEREBY THE BED IS CAPABLE OFLATERAL FLOW, DISCHARGING A MIXTURE OF HOT FINELY DIVIDED COKE ANDRESIDUAL OIL INTO THE COKING ZONE AT ONE END OF THE COKE BED WHEREBY THEADDED COKE MERGES WITH THE COKE BED AND THE RESIDUAL OIL IS PARTLYVAPORIZED BY THE HEAT OF THE ADDED HOT COKE AND THE UNVAPORIZED PORTIONIS DEPOSITED ON THE SURFACES OF HOT COKE PARTICLES FOR DISTILLATION ANDDECOMPOSITION BY THE HEAT OF THE COKE CONTINUOUSLY STRIPPING SAID OILVAPORS FROM SAID HORIZONTALLY FLOWING BED BY MEANS OF SAID AERATING GASTO DIMINISH THE AMOUNT OF OIL VAPOR IN SAID BED AS IT FLOWS DOWNSTREAM,MAINTAINING A DISENGAGING SPACE ABOVE SAID HORIZONTALLY FLOWING BED FORCOLLECTING SAID VAPORIZED